أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا عَبْدُ الْوَهَّابِ، قَالَ سَمِعْتُ يَحْيَى بْنَ سَعِيدٍ، يَقُولُ سَمِعْتُ نَافِعًا، يُحَدِّثُ عَنِ ابْنِ عُمَرَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏"‏ إِنَّ الْمُتَبَايِعَيْنِ بِالْخِيَارِ فِي بَيْعِهِمَا مَا لَمْ يَفْتَرِقَا إِلاَّ أَنْ يَكُونَ الْبَيْعُ خِيَارًا ‏"‏ ‏.‏ قَالَ نَافِعٌ فَكَانَ عَبْدُ اللَّهِ إِذَا اشْتَرَى شَيْئًا يُعْجِبُهُ فَارَقَ صَاحِبَهُ ‏.‏

It was narrated from Yahya bin Sa 'eed who said: "I heard Nafi narrating from Ibn 'Umar, form the Messenger of Allah 'the two parties to a transaction both have the choice so long as they have not separated unless they have chosen to conclude the transaction. " Nafi said: ''When 'Abdullah bought something he like, he would leave straightaway." Translation Not Available

Book Ref: Sunan An Nisai Book 44 Hadith 4473
Web Ref:  Sunan An Nisai Vol 5 Book 44 Hadith 4478